Quick cars on small(er) carbs?

[jamiep_jamiep]

Have a buddy with a 2276 on 44 IDF's, and he's working towards hopefully getting it into the 12's - it's stock weight more or less and currently runs mid 13's. He's experiencing a fairly sharp drop off in power after 5500rpm, presumably down to the carbs choking him off - they're on 36 Vents.  Runs I think an 86B cam and 42x37 heads. What tricks could he do to the carbs to maybe massage a little more power - I see a 40mm vent is available, presumably these would help?

[Zach Gomulka]

40's should help but why not just swap the carbs for 48IDF's? Same bolt pattern. Is the exhaust big enough?

[Torben Alstrup]

44´s don´t like more than 38 mm venturies if it has to be driveable on the street too... But yes it will help some. It is quite normal that such an engine flattrens out at just over 5500. Dependant on how the heads are done that is about where they hit the wall with that displacement versus cam duration.

T

[modnrod]

Heads.

[richie]

How long since its been put together? how many miles? valve springs might be failing now

cheers Richie

[benlawrence]

12's is easy doable on 44's. Last year i did a tune on a mates engine on some chinese copies. Spec was the usual off the shelf 82x94 10-1 wedgeport 86c motor ( easy 180- 200bhp combo ) . It originally pulled 150 ish through the stock 36mm vents and crappy muffler. Richie and Jo sent us out one of their nice merged mufflers and i ordered up a set of 40mm vents and chucked it all together. Headed over to my friends at the dyno and after a few jetting changes we ended up with 187bhp belt on. As Torben has mentioned above the big vents really hurt driveability down low, far more so than if you were on an ida, but i was shooting for all out power not driveability, perhaps with more time i could have smoothed it out but thats for another day. You can make plenty of power on 44's, i would say a big percentage of street motors dont even warrant running an ida and 44's with the appropriate vents more than get the job done.
Just my 2c.

[Udo]

I have build a 2276 with 195 HP on 44 IDF's That should be enough to come into the 12's . Good heads and FK10 was the key :-)

Udo

[jamiep_jamiep]

Thanks for the input folks, he's readin this and has taken it on board